CELEBRITY chef Gordon Ramsay is in hot water – and it’s got nothing to do with cooking, according to a startling news report.

Ramsay has been having a seven-year affair with Britain’s most famous mistress, the News of the World said today.

The woman in the sex scandal is Sarah Symonds, who has had so many affairs with powerful married men in Britain that she wrote a book about it, called “Having an Affair: A Handbook for the Other Woman.”

Symonds was even interviewed on “Oprah” as a sort of role model for aspiring mistresses.

The paper published a photo of Ramsay leaving a high-priced London hotel this week after spending what it said was 75 minutes in Symond’s $600-a-night room.

Earlier in the day, a reporter for the paper followed Symonds to a nearby sex shop where she bought amyl nitrate, a legal drug often used to enhance sex play.

The paper reported that the tyrannical chef, who stars in “Hell’s Kitchen” and “Kitchen Nightmares,” and Symonds had also met the week before at the same hotel, located next door to one of Ramsay’s most popular restaurants, The Maze.

The affair began in 2001 after the couple met at a London nightclub, it was reported. At that moment, Symonds was more famous than Ramsay because she had been revealed as the mistress of suspense novelist and conservative politician Jeffrey Archer. Archer was running for mayor of London at the time.

The affair with Ramsay went on in LA and London. Ramsay even brought Symonds to the restaurant set of “Hell’s Kitchen,” where she posed as a dinner guest, the paper reported.

The foul-mouthed chef has carefully constructed a public image for himself as a family man – married for 12 years to a former Montessori schoolteacher, Tana, with four kids.

Phone messages and emails to Ramsay’s New York PR agency were not returned today.

Symonds told a News of the World reporter: “Sorry, I’ve got nothing to say on the matter.”